House Martell of Sunspear is one of the Great Houses of Westeros and the principal noble house of Dorne. Where the other paramount houses style themselves Lord, the head of House Martell is styled Prince, a custom inherited from Nymeria of the Rhoynar, who beached ten thousand ships on the Dornish shore and took Lord Mors Martell to husband. Together they conquered all Dorne and joined two peoples into one.
For two centuries Martell Dorne defied the Iron Throne. Where the rest of Westeros bent its knee to Aegon's dragons, the Dornishmen melted into their deserts and fought a war of arrows and shadows the dragons could not win. They were not brought into the realm by conquest at all but by marriage, more than a century later. By the events of A Game of Thrones Prince Doran Martell rules from Sunspear in patient quiet, while his younger brother Oberyn, the Red Viper, burns at the slow rate of his name for the Lannister hands that broke his sister Elia.